The present invention relates generally to air conditioners and more specifically to a fan motor brown-out control algorithm for accommodating under-voltages supplied to an air conditioner.
The occurrence of what is known as a brown-out power condition is fairly common, especially in power distribution systems incapable of accommodating peak loads during high power demand situations. A brown-out is a power condition in which the voltage supplied by a power station is less than the standard supplied voltage. A brown-out is not as serious as a black-out in which the supplied voltage is reduced to zero. However, the under-voltage condition of a brown-out is very inconvenient because the connected electrical appliances are less effective, if even operable, at the lower brown-out voltage level.
As a result, the use of electrical appliances that are commonly prone to brown-outs becomes problematic. For example, when an air conditioner is running on medium speed and a brown-out occurs, the air conditioner effectively operates as if it is running at low speed or may have trouble operating at all. Thus, a user must continuously adjust the fan manually to a higher speed to compensate for the brown-out condition. This is time-consuming and often not even possible due to the location of the air conditioner relative to the reach of the user.
U.S. Pat. No. 4,354,214 discloses a motor control circuit, which upon detecting an under-voltage, shuts down the motor completely. Similarly, U.S. Pat. No. 3,946,574 discloses an under-voltage sensing circuit which entirely shuts down a compressor if a low-voltage condition is detected. In addition, U.S. Pat. No. 4,453,117 discloses a computerized motor control system which protects the control memory in case of a voltage brown-out condition.
Thus, the prior art solutions to a brown-out condition shut the motor off upon sensing a brown-out condition. This approach is unacceptable because it renders the motor or fan totally inoperable since it has been shut off.
As a result, a need has arisen for a fan motor brown-out control algorithm to accommodate the proper operation and use of electrical appliances in areas prone to brown-out conditions.